Transfer of Rhodamine-123 into the Brain and Cerebrospinal Fluid of Fetal, Neonatal and Adult Rats

Abstract Background: Adenosine triphosphate binding cassette transporters such as P-glycoprotein (PGP) play an important role in drug pharmacokinetics by actively effluxing their substrates at barrier interfaces, including the blood-brain, blood-cerebrospinal fluid (CSF) and placental barriers. For a molecule to access the brain during fetal stages it must bypass efflux transporters at both the placental barrier and brain barriers themselves. Following birth, placental protection is no longer present and brain barriers remain the major line of defense. Understanding developmental differences that exist in the transfer of PGP substrates into the brain is important for ensuring that medication regimes are safe and appropriate for all patients. Methods: In the present study PGP substrate rhodamine-123 (R123) was injected intraperitoneally into E19 dams, postnatal (P4, P14) and adult rats. Naturally fluorescent properties of R123 were utilized to measure its concentration in blood-plasma, CSF and brain by spectrofluorimetry (Clariostar). Statistical differences in R123 transfer (ratios between tissue and plasma concentrations) were determined using Kruskal-Wallis tests with Dunn’s corrections. Results: Following maternal injection the transfer of R123 across the E19 placenta from maternal blood to fetal blood was around 20%. Of the R123 that reached fetal circulation 41% transferred into brain and 38% into CSF. The transfer of R123 from blood to brain and CSF was lower in postnatal pups and decreased with age (brain: 43% at P4, 22% at P14 and 9% in adults; CSF: 8% at P4, 8% at P14 and 1% in adults). Transfer from maternal blood across placental and brain barriers into fetal brain was approximately 8%, similar to the transfer across adult blood-brain barriers (9%). Following birth when placental protection was no longer present, transfer of R123 from blood into the newborn brain was significantly higher than into adult brain (3 fold, p<0.05). Conclusions: Administration of a PGP substrate to infant rats resulted in a higher transfer into the brain than equivalent doses at later stages of life or equivalent maternal doses during gestation. Toxicological testing of PGP substrate drugs should consider the possibility of these patient specific differences in safety analysis. Trial Registration: N/A.

Download Full-text

Transfer of rhodamine-123 into the brain and cerebrospinal fluid of fetal, neonatal and adult rats

Fluids and Barriers of the CNS ◽

10.1186/s12987-021-00241-8 ◽

2021 ◽

Vol 18 (1) ◽

Author(s):

Liam M. Koehn ◽

Katarzyna M. Dziegielewska ◽

Mark D. Habgood ◽

Yifan Huang ◽

Norman R. Saunders

Keyword(s):

Cerebrospinal Fluid ◽

Fetal Brain ◽

Maternal Blood ◽

Adult Brain ◽

Rhodamine 123 ◽

Patient Specific ◽

Adult Rats ◽

Blood Brain ◽

The Brain ◽

Brain Barriers

Abstract Background Adenosine triphosphate binding cassette transporters such as P-glycoprotein (PGP) play an important role in drug pharmacokinetics by actively effluxing their substrates at barrier interfaces, including the blood-brain, blood-cerebrospinal fluid (CSF) and placental barriers. For a molecule to access the brain during fetal stages it must bypass efflux transporters at both the placental barrier and brain barriers themselves. Following birth, placental protection is no longer present and brain barriers remain the major line of defense. Understanding developmental differences that exist in the transfer of PGP substrates into the brain is important for ensuring that medication regimes are safe and appropriate for all patients. Methods In the present study PGP substrate rhodamine-123 (R123) was injected intraperitoneally into E19 dams, postnatal (P4, P14) and adult rats. Naturally fluorescent properties of R123 were utilized to measure its concentration in blood-plasma, CSF and brain by spectrofluorimetry (Clariostar). Statistical differences in R123 transfer (concentration ratios between tissue and plasma ratios) were determined using Kruskal-Wallis tests with Dunn’s corrections. Results Following maternal injection the transfer of R123 across the E19 placenta from maternal blood to fetal blood was around 20 %. Of the R123 that reached fetal circulation 43 % transferred into brain and 38 % into CSF. The transfer of R123 from blood to brain and CSF was lower in postnatal pups and decreased with age (brain: 43 % at P4, 22 % at P14 and 9 % in adults; CSF: 8 % at P4, 8 % at P14 and 1 % in adults). Transfer from maternal blood across placental and brain barriers into fetal brain was approximately 9 %, similar to the transfer across adult blood-brain barriers (also 9 %). Following birth when placental protection was no longer present, transfer of R123 from blood into the newborn brain was significantly higher than into adult brain (3 fold, p < 0.05). Conclusions Administration of a PGP substrate to infant rats resulted in a higher transfer into the brain than equivalent doses at later stages of life or equivalent maternal doses during gestation. Toxicological testing of PGP substrate drugs should consider the possibility of these patient specific differences in safety analysis.

Download Full-text

The Potential Roles of Blood–Brain Barrier and Blood–Cerebrospinal Fluid Barrier in Maintaining Brain Manganese Homeostasis

Nutrients ◽

10.3390/nu13061833 ◽

2021 ◽

Vol 13 (6) ◽

pp. 1833

Author(s):

Shannon Morgan McCabe ◽

Ningning Zhao

Keyword(s):

Cerebrospinal Fluid ◽

Blood Brain Barrier ◽

Blood Circulation ◽

Critical Role ◽

Systemic Circulation ◽

Brain Parenchyma ◽

Brain Barrier ◽

Blood Brain ◽

The Brain

Manganese (Mn) is a trace nutrient necessary for life but becomes neurotoxic at high concentrations in the brain. The brain is a “privileged” organ that is separated from systemic blood circulation mainly by two barriers. Endothelial cells within the brain form tight junctions and act as the blood–brain barrier (BBB), which physically separates circulating blood from the brain parenchyma. Between the blood and the cerebrospinal fluid (CSF) is the choroid plexus (CP), which is a tissue that acts as the blood–CSF barrier (BCB). Pharmaceuticals, proteins, and metals in the systemic circulation are unable to reach the brain and spinal cord unless transported through either of the two brain barriers. The BBB and the BCB consist of tightly connected cells that fulfill the critical role of neuroprotection and control the exchange of materials between the brain environment and blood circulation. Many recent publications provide insights into Mn transport in vivo or in cell models. In this review, we will focus on the current research regarding Mn metabolism in the brain and discuss the potential roles of the BBB and BCB in maintaining brain Mn homeostasis.

Download Full-text

Lead Exposure in Developmental Ages Promotes Aβ Accumulation by Disturbing Aβ Transportation in Blood-Cerebrospinal Fluid Barrier/Blood–Brain Barriers and Impairing Aβ Clearance in the Liver

Biological Trace Element Research ◽

10.1007/s12011-021-02969-8 ◽

2021 ◽

Author(s):

Can-Can Zhou ◽

Xu-Jie Wang ◽

Zi-Chen Li ◽

Wen-Jie Lu ◽

Yun-Ting Zhang ◽

...

Keyword(s):

Cerebrospinal Fluid ◽

Lead Exposure ◽

Blood Brain ◽

Aβ Clearance ◽

Brain Barriers

Download Full-text

The impact of hypoxia on blood-brain, blood-CSF and CSF-brain barriers

Journal of Applied Physiology ◽

10.1152/japplphysiol.00108.2020 ◽

2021 ◽

Author(s):

Jeff F. Dunn ◽

Albert M Isaacs

Keyword(s):

Multiple Sclerosis ◽

Cerebrospinal Fluid ◽

Cellular Structures ◽

Bacterial Toxin ◽

Blood Brain ◽

High Altitude Cerebral Edema ◽

The Central Nervous System ◽

Neurological Conditions ◽

The Impact ◽

Brain Barriers

The blood-brain barrier (BBB), blood-cerebrospinal fluid barrier (BCSFB) and CSF-brain barriers (CSFBB) are highly regulated barriers in the central nervous system comprising of complex multi-cellular structures that separate nerves and glia from blood and cerebrospinal fluid, respectively. Barrier damage has been implicated in the pathophysiology of diverse hypoxia-related neurological conditions including stroke, multiple sclerosis, hydrocephalus and high-altitude cerebral edema. Much is known about damage to the BBB in response to hypoxia but much less is known about the BCSFB and CSFBB. Yet it is known that these other barriers are implicated in damage after hypoxia or inflammation. In the 1950s, it was shown that the rate of radionucleated human serum albumin passage from plasma to CSF was 5-times higher during hypoxic than normoxic conditions in dogs, due to blood-CSF barrier disruption. Severe hypoxia due to administration of the bacterial toxin, lipopolysaccharide (LPS) is associated with disruption of the CSFBB. This review discusses the anatomy of the BBB, BCSFB and CSFBB, and the impact of hypoxia and associated inflammation on the regulation of those barriers.

Download Full-text

The Presence of Caffeic Acid in Cerebrospinal Fluid: Evidence That Dietary Polyphenols Can Cross the Blood-Brain Barrier in Humans

Nutrients ◽

10.3390/nu12051531 ◽

2020 ◽

Vol 12 (5) ◽

pp. 1531 ◽

Cited By ~ 3

Author(s):

Izabela Grabska-Kobylecka ◽

Justyna Kaczmarek-Bak ◽

Malgorzata Figlus ◽

Anna Prymont-Przyminska ◽

Anna Zwolinska ◽

...

Keyword(s):

Cerebrospinal Fluid ◽

Caffeic Acid ◽

Blood Brain Barrier ◽

Solid Phase ◽

Plasma Concentrations ◽

Brain Barrier ◽

Facilitated Diffusion ◽

Dietary Polyphenols ◽

Brain Functions ◽

Blood Brain

Epidemiological data indicate that a diet rich in plant polyphenols has a positive effect on brain functions, improving memory and cognition in humans. Direct activity of ingested phenolics on brain neurons may be one of plausible mechanisms explaining these data. This also suggests that some phenolics can cross the blood-brain barrier and be present in the brain or cerebrospinal fluid. We measured 12 phenolics (a combination of the solid-phase extraction technique with high-performance liquid chromatography) in cerebrospinal fluid and matched plasma samples from 28 patients undergoing diagnostic lumbar puncture due to neurological disorders. Homovanillic acid, 3-hydroxyphenyl acetic acid and caffeic acid were detectable in cerebrospinal fluid reaching concentrations (median; interquartile range) 0.18; 0.14 µmol/L, 4.35; 7.36 µmol/L and 0.02; 0.01 µmol/L, respectively. Plasma concentrations of caffeic acid (0.03; 0.01 µmol/L) did not correlate with those in cerebrospinal fluid (ρ = −0.109, p = 0.58). Because food (fruits and vegetables) is the only source of caffeic acid in human body fluids, our results indicate that the same dietary phenolics can cross blood-brain barrier in humans, and that transportation of caffeic acid through this barrier is not the result of simple or facilitated diffusion.

Download Full-text

Age-Associated Changes in the Immune System and Blood–Brain Barrier Functions

International Journal of Molecular Sciences ◽

10.3390/ijms20071632 ◽

2019 ◽

Vol 20 (7) ◽

pp. 1632 ◽

Cited By ~ 25

Author(s):

Michelle Erickson ◽

William Banks

Keyword(s):

Central Nervous System ◽

Immune System ◽

Blood Brain Barrier ◽

Neurological Disorders ◽

Brain Barrier ◽

Immune Functions ◽

Blood Brain ◽

The Brain ◽

Brain Barriers

Age is associated with altered immune functions that may affect the brain. Brain barriers, including the blood–brain barrier (BBB) and blood–CSF barrier (BCSFB), are important interfaces for neuroimmune communication, and are affected by aging. In this review, we explore novel mechanisms by which the aging immune system alters central nervous system functions and neuroimmune responses, with a focus on brain barriers. Specific emphasis will be on recent works that have identified novel mechanisms by which BBB/BCSFB functions change with age, interactions of the BBB with age-associated immune factors, and contributions of the BBB to age-associated neurological disorders. Understanding how age alters BBB functions and responses to pathological insults could provide important insight on the role of the BBB in the progression of cognitive decline and neurodegenerative disease.

Download Full-text

Expression of the Cystathionine β Synthase (CBS) Gene During Mouse Development and Immunolocalization in Adult Brain

Journal of Histochemistry & Cytochemistry ◽

10.1177/002215540305100311 ◽

2003 ◽

Vol 51 (3) ◽

pp. 363-371 ◽

Cited By ~ 94

Author(s):

Karine Robert ◽

François Vialard ◽

Eric Thiery ◽

Kiyoko Toyama ◽

Pierre-Marie Sinet ◽

...

Keyword(s):

Plasma Concentrations ◽

Northern Blotting ◽

Adult Brain ◽

Spatial And Temporal Patterns ◽

Mouse Development ◽

Cellular Expression ◽

Brain Expression ◽

Neuronal Processes ◽

The Brain

Hyperhomocysteinemia, caused by a lack of cystathionine β synthase (CBS), leads to elevated plasma concentrations of homocysteine. This is a common risk factor for atherosclerosis, stroke, and possibly neurodegenerative diseases. However, the mechanisms that link hyperhomocysteinemia due to CBS deficiency to these diseases are still unknown. Early biochemical studies describe developmental and adult patterns of transsulfuration and CBS expression in a variety of species. However, there is incomplete knowledge about the regional and cellular expression pattern of CBS, notably in the brain. To complete the previous data, we used in situ hybridization and Northern blotting to characterize the spatial and temporal patterns of Cbs gene expression during mouse development. In the early stages of development, the Cbs gene was expressed only in the liver and in the skeletal, cardiac, and nervous systems. The expression declined in the nervous system in the late embryonic stages, whereas it increased in the brain after birth, peaking during cerebellar development. In the adult brain, expression was strongest in the Purkinje cell layer and in the hippocampus. Immunohistochemical analyses showed that the CBS protein was localized in most areas of the brain but predominantly in the cell bodies and neuronal processes of Purkinje cells and Ammon's horn neurons.

Download Full-text

Antimicrobial Penetration into Cerebrospinal Fluid

Drug Intelligence & Clinical Pharmacy ◽

10.1177/106002808101500505 ◽

1981 ◽

Vol 15 (5) ◽

pp. 341-368 ◽

Cited By ~ 12

Author(s):

Mark L. Richards ◽

Randall A. Prince ◽

Karen A. Kenaley ◽

Jeanine A. Johnson ◽

Jack L. LeFrock

Keyword(s):

Cerebrospinal Fluid ◽

Blood Brain Barrier ◽

Brain Barrier ◽

Cns Infections ◽

Blood Brain ◽

The Brain

The complex physiology of the blood-brain barrier and the characteristics of an antimicrobial which govern its distribution into the brain are poorly understood. Likewise, available data regarding CSF antimicrobial concentrations after extra-CNS administration, as tabulated in this review, are inadequate. Because of the potentially dire consequences that result from inappropriately treated CNS infections, large cooperative studies using standardized methodology are needed. Suggestions for such methods are outlined.

Download Full-text